This invention relates to a high tenacity polyhexamethylene adipamide yarn having a ribbon cross-section as a covering yarn for spandex yarn in women's hosiery and a process for making said covering yarn.
Pantyhose manufacturers have made stockings typically in which spandex with a single covering of textured 15 to 20 denier nylon is knit in alternate courses with a non-textured 15 to 20 denier nylon yarn. Due to the relatively high expense of texturing, it was desirable to develop a covering yarn without the need for texturing. A 6-nylon yarn and a 6.6 nylon yarn each having a ribbon cross-section and used as a covering yarn are known. Because the ribbon cross-section provides a very low bending modulus it facilitates wrapping around the spandex, eliminating the need for expensive textured yarn and requiring about two-thirds the normal covering turns per inch to protect the spandex. However, the 6.6 nylon yarn proved unacceptable due to low yarn tenacity which resulted in low hose burst-strength and wear life. It would be desirable to increase the tenacity and thus the burst-strength and wear life while maintaining a ribbon or high length to width ratio cross-section of the constituent filaments of the yarn.
It is an object of this invention to develop a polyhexamethylene adipamide yarn and a process for producing such yarn with a high tenacity and with constituent filaments having a cross-section with a high length to width ratio.